LQ9 Pulsed Cooling Fan output?

[HzEmall]

I have a LQ9 swapped in to my 79 C-10 with the Painless harness. It uses the OEM ECM and it sends out a cooling fan signal when it reaches temp and kicks on a 30 amp relay in the Painless Gen III fuse/relay box.

BUT, when it get to temp and kicks in the relay opens and closes none stop, sound like the turn signals are on.

Has anyone run into this? I can't see anything in the HP Tuner software that would make a difference with it.....

Thanks

[ls1nova71]

Are your fan on and off temps set to the same temperature?
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[mooseknuckles]

I had a similar problem....the one fan relay was set to come on at 180* and it works, but number two fan relay would be clicking some times, so I thought it was the relay, so I switched it with another and now it doesn't do it anymore....not sure if the second fan is working, I've never had it come on....

[BR3W CITY]

You didn't somehow get a flasher instead of a relay...right? I'm mostly kidding.


I've seen both fans run off of one input, which works. If you run 2 fans, isn't the second fan only supposed to come on with the a/c loaded?

[mooseknuckles]

lol..I have two separate wires for fans from the pcm, each one wired to a relay...from what I've been told, the second fan only comes on if the first one cant keep it cool?....and it's never come on, which is a good thing right?

[1BadAction]

How fast is it pulsing? That sounds like how the electro-viscous clutch fan control works. What ECM and OS are you running? You should see a fan table (if HPT has it) that says something like 0% to 100% fan, my first thought would be to make that either 100% or 0% so it's not pulsing, but I'm not sure how the ECM would handle that...

[HzEmall]

i dont remember which ecm but its either the 89017733, 12576106 or the 12583560. Those are the ones Painless requires you to use with their harness. It's all based off of the 2002 4.8 parts I am told (ecm, tac, pedal etc)

It's clicking as fast as a turn signal flasher would. I swapped out the relay for another one and it still does it so it's something in the ECM I am guessing.

[ls1nova71]

So do you have HPTuners? In your first post you stated that you didn't see anything in it that would make a didifference, which leads me to believe you do, so I would try lowering the fan off temp.
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[HzEmall]

The cut off temp was higher then the turn on temp so I lowered it to see how it will do now.

[ls1nova71]

Originally Posted by HzEmall

The cut off temp was higher then the turn on temp so I lowered it to see how it will do now.

The turn off temp should be lower than the turn on temp. For example if they come on at 210 if your off temp was 215 it would come on at 210 but since it sees the temp below 215 it would turn right back off, and so on and so on. If your on temp was 210 and your off was say 185., the fan would come on at 210 and continue to run until it cooled the temp down to 185.
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[Shon]

Could be that the PCM is not told correctly that there are 2 fans.
This happened to me recently. #1 fan come on as it supposed to, #2 would click the relay. Checked wiring and all was good. Went back into HPT and found that you have to tell it there are fans now, which if #1 is coming on that has been done. and for #2 to work there is a tab/section for #2 fan to come on, its something to do with A/C function, I do not have HPT here so I can not look at.
I did not notice this until I went to Beta HPT. Wondering if my 71 has this issue, but it never gets above 210; the one fan cools it down. I just happened to notice it in the stang b/c the relay/fuse block is going to be under the passenger seat.

[DavidB]

Yea I ran into this too. If you have the new beta hptuner. (if you have the old they will upgrade you for free) you have the option to turm off the ac signal and control the high fan output with that wire like Camaro PCM does.
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[loweredd]

I came across this in a search tonight for a primary fan relay clicking like a flasher while the fan was on. The OFF temperature WAS higher than the ON temperature. A few quick changes in HPTuners and the clicking was gone.